Maximum recursion depth exceeded due to self-reference in associate statement

[Friedinho]

I encountered an issue, where an accidental self reference in an associate statement lead to crashing the language server. Maybe this is not a classical bug, but it would be nice, if it is catched somehow.

The error stated that the maximum recursion depth exceeded. Since I did not know, where the error came from, I increased the depth limit. The error then showed that the language server failed to create a connection.

I my (relative) large program, the server did not responed and I could not use ay features, such as hover or jump to subroutines. Creating a minimal working example, it shows the error, but it still workes kind of. Try to hover over the associate(realsAndIntegers => realsAndIntegers) within this program:

module someTypes
   implicit none
   private

   public integer_type
   public realAndInteger_type
   
   type integer_type
   integer(4) :: a
   end type integer_type
   
   type realAndInteger_type
   real(8) :: b
   type(integer_type) :: c
   end type realAndInteger_type
end module someTypes

module errorModule
   use someTypes
   
   implicit none
   private
   
   public error_inHere
contains
   subroutine error_inHere(realsAndIntegers, integers)
   type(realAndInteger_type), intent(inout) :: realsAndIntegers
   type(integer_type),               intent(inout) :: integers
      ! error here !
      associate(realsAndIntegers => realsAndIntegers)
         realsAndIntegers%b = 1.0
         realsAndIntegers%c%a = 1
      end associate
      integers%a = 2
   end subroutine error_inHere
end module errorModule


program error_main

use someTypes
use errorModule

implicit none

type(integer_type)               :: my_integers
type(realAndInteger_type) :: my_realsAndIntegers

   call error_inHere(my_realsAndIntegers, my_integers)
   print *, my_integers%a
   print *, my_realsAndIntegers%b, my_realsAndIntegers%c%a

end program error_main

The error is within the minimal example:

[Error - 10:45:31 AM] Request textDocument/hover failed.
  Message: maximum recursion depth exceeded
  Code: -32603 
[object Object]
[WARN - 10:45:31] error handling request {'jsonrpc': '2.0', 'id': 1290, 'method': 'textDocument/hover', 'params': {'textDocument': {'uri': 'file:///home/jf/Desktop/temp/modernFortran_fail/error_main.F90'}, 'position': {'line': 31, 'character': 22}}}
Traceback (most recent call last):
  File "/home/jf/.local/lib/python3.9/site-packages/fortls/langserver.py", line 173, in handle
    resp = handler(request)
  File "/home/jf/.local/lib/python3.9/site-packages/fortls/langserver.py", line 1112, in serve_hover
    var_type: int = var_obj.get_type()
  File "/home/jf/.local/lib/python3.9/site-packages/fortls/parsers/internal/variable.py", line 89, in get_type
    return self.link_obj.get_type()
  File "/home/jf/.local/lib/python3.9/site-packages/fortls/parsers/internal/variable.py", line 89, in get_type
    return self.link_obj.get_type()
  File "/home/jf/.local/lib/python3.9/site-packages/fortls/parsers/internal/variable.py", line 89, in get_type
    return self.link_obj.get_type()
  [Previous line repeated 992 more times]
RecursionError: maximum recursion depth exceeded

The error code produced with my actual program is a little bit longer and the location of the erorr was not shown.
The system is openSUSE Leap 15.4 with VSCode 1.92.4, fortls 3.1.2, Modern Fortran v3.4.2024090901 and gfortran 12.0 compiler. I am using the standard settings and do not have any special configurations, which may affect the error.